Vent cap for gas heating structure



Oct. l2, i965 VENT Filed June 25, 1964 R. E. CARLSON CAP FOR GAS HEATING STRUCTURE 2 Sheets-Sheet 1 Oct. l2, 1965 R. E. CARLSON VENT GAP FOR GAS HEATING STRUCTURE 2 Sheets-Sheet 2 Filed June 25, 1964 United States Patent O This invention relates to gas tired heaters with sealed combustion chambers especially for house trailers, cabins, yachts, homes, cabin crusiers, sailboats and the like. This application is a continuation-in-part of my earlier application, Ser. No. 201,441, led lune 11, 1962.

With heaters of the type to which this invention is applii cable, combustion air to supply the gas burners in the sealed combustion chambers is drawn from the outside air rather than from the interiors of the spaces being heated. With such heaters it is also the practice to vent the combustion chambers laterally from the upper portions thereof out through the buildings sidewalls, and to draw the outside combustion air through a concentric air pipe surrounding the vent pipe.

Lateral venting with concentric horizontal piping has heretofore been deemed to be t-he only satisfactory construction for heaters with sealed combustion chambers, apparently because it has been thought that fresh combustion air ow to the combustion chamber could be satisfactorily accomplished only by horizontal flow at a low level from the exterior of the structure to be heated.

However, such heater constructions have various objections, including the sidewall venting, variable draft conditions, and hot vent caps at low levels outside.

It is a general object of this invention to provide a space heating and venting means which eliminate all such objections. It is a particular object of this invention to provide a space heating structure which is vented through the roof and at the same time to employ a vent cap which retains the concentric piping arrangement of sidewall venting, the outside combustion air being brought down around the Ihot vent pipe from a position above the roof, rain being effectually excluded, and mixing of incoming air wit-h exhaust gases being etfectually prevented.

Still another object of the invention is to transfer the typical vent cap to an elevated position so that such vent cap, which often becomes quite hot, is not in a position to burn persons passing the side of the building as where horizontal piping is vented.

A further object is to provide a vertical venting and piping arrangement extending through the roof wherein a vent cap structure is employed which not only diverts rain or water spray from entering the exhaust venting pipe, but also covers the cool air intake pipe to guard it against the entry of rain or spray.

Briefly outlined, the present improvement includes an upstanding two-element heating member disposed vertically in a shallow casing or housing often known as a linen The forward element of the heating member constitutes a sealed re box or combustion chamber at the lower end of which a burner is positioned and at the upper end of which there is an outlet passage to a vertical ilue or vent pipe mounted on the heating member and extending up through the buldings roof to vent the combustion gases. The other element of the heating member is a ilattened air chamber element disposed behind the lire box or combustion chamber, both elements being attached to an intervening radiation partition. This ilattened chamber element is in the form of an air supply chamber enclosed on all sides and at its top and bottom, except that its top provides an intake opening for cool air and its forward wall at the bottom provides an opening connected by an air duct to the lower portion of the 3,211,079 Patented Oct. 12, 1965 rice combustion chamber to feed such cool air to the burner to support combustion. The upper end of the air chamber is provided with an air intake duct which leads downward from an annular space within a collar upstanding from the heater member and receiving the lower end of an outer concentric air intake pipe leading down from the roof around the exhaust pipe.

Above the roof, the top of the exhaust pipe carries a vent cap under which the spent combustion gases are discharged, such cap having plate means arranged to prevent Imixing of exhaust gases with incoming air and having special means such as a vertical ring for excluding rain or spray from the exhaust pipe and also guarding the air intake pipe to exclude rain or spray therefrom. Thus, pre-warmed cool air is fed from above the roof down through the annular space between the exhaust pipe and the air intake pipe where it enters the upper end of the air chambers whence it passes to the lower end ofthe combustion chamber, the spent combustion gases then rising through the outlet from the combustion chamber into the central exhaust pipe by which they are discharged through the roof by way of the vent cap which both excludes rain and prevents mixing of the spent combustion gas with down-draft cold air moving to the combustion chamber. Convection air rises around the combustion chamber in front of the radiation partition, and also rises around the intake air chamber which is heated by radiation from the combustion chamber via the radiation partition, such heated air passing forward and outward through the upper portion of a grill or front panel into the living space of the building, radiation heat being projected directly forward from the combustion chamber through the grill into such living space.

Further objects and features of the invention will become apparent to those skilled in the artjupon reference to the following specification and the accompanying drawings wherein a presently preferred form of the invention is disclosed.

In the drawings:

FIG. l is a prespective view of the vent cap and heating structure of lthis invention disclosed as installed in a wall of a small building, portions of the wall being broken away;

FIG. 2 is a vertical section from front to back taken as indicated by the line 2 2 of FIG. 1;

FIG. 3 is a cross-sectional view through an intermediate portion ofthe heater;

FIG. 4 is a vertical section on an enlarged scale through the vent cap hereof; and

FIG. 5 is a similar view of a varied assemblage.

The present improvement is shown especially in the upper portion of FIG. 2 and in FIG. 4 which illustrates the arrangement of the Vent cap and air supply and exhaust pipes upstanding from the top of the heater.

As indicated, the entire heating structure is arranged for installation within a wall of a house trailer or the like in which it is to be used. Whereas laterally vented gas heaters must be disposed in an outer wall, the present structure, being vented through the roof with the vent cap above the roof, may be mounted in an interior wall.

With particular reference to the drawings, a Wall structure is illustrated as including a typical rearward wall panel 10, a forward or inner wall panel 12, a roof panel 14 or other roof structure, and a pair of upstanding supporting and spacing studs 1S, all of which are carried on an appropriate lloor structure 18. l

A primary heating member or unit generally indicated at 20, which is illustrated as an upstanding gas red sheet metal structure, is supported in a rectangular housing or liner 22, also metal, from which there upstands a pipe assemblage 24 having an outer vent cap assembly 25 above the roof 14. The pipe assemblage includes a central exhaust pipe 26 and an outer concentric air feed pipe 28 affording an annular cold-air conducting channel 30. Desirably, there is also an intervening concentric radiation pipe 32 which provides an inner annular air channel 34, whereby further to reduce the temperature of the air pipe 28. These pipes 26, 28, and 32 are flxedly carried by the top of the heater unit 20.

The heater unit includes two spaced upstanding connected elements. The forward element 35 provides an enclosed combustion chamber 36 having a forward upper wall portion parallel to forward and rearward parallel walls of a rearward element 38 which provides an enclosed cold-air supplying chamber 39. Both of these elements 35 and 38 are, in general, rectangular in design similar to the rectangular construction of the housing 22, but they are appreciably smaller in order to be mounted in spaced relation in the housing 22 and provide adequate air circulation spaces around them. Also the elements 35 and 38 are rigidly connected. At their lower ends, this rigid connection is made through the medium of a connecting air tube 40 welded to the opposing walls of the two elements and providing a duct to feed cool air from the lower end of the air passing chamber 39 to the lower end of the combustion chamber 36 which contains at such lower end a burner 42 of any desired construction. The upper portion of the burner is disposed between two opposed bafiies 43 which control the flame. The upper ends of the elements 35 and 36 are rigidly connected by welding thereto a metal rectangular approximately cubical box 44 whose bottom wall 45 is provided with a circular opening or port 46 around which is welded to the bottom 45 the lower end portion of the exhaust pipe 26. Rearward of the circular opening or port 46, the bottom 45 of such box is also provided with a transverse rectangular opening or port 48 which provides an air feed passage into the top of the air chamber 39 of the reaward element 38.

The rearward element 38 provides a vertical elongated rectangular passage constituting the air chamber 39 formed between a back wall 50 and a front wall 51 of the element 38, such passage extending from the inlet port 48 down to the air discharge duct 40 which feeds fresh air to the burner. The back wall 50 and the back wall of the box 44 are thus in substantial vertical alignment. In this manner, a constant supply of cool air is supplied from the annular channel 30, and also from the annular channel 34 if the radiation tube 32 is used, down into the cool-air chamber 39 by way of the rectangular port 48 and thence via the duct 40 to the burner 42.

The forward wall of the metal box 44 is in approximate vertical alignment with the back wall of the heater element 35. Upon the top of the box 44 there is welded a nearly square or rectangular plate or top wall 54 which fits under the top 55 of the housing 22 when the parts are in the assembled relation illustrated. This plate 54 has welded on the top thereof a collar 56 over which the lower end of the outer air pipe 28 fits. The greater portion of the plate 54 is provided with a rectangular opening or port 58 located within the confines of the collar 56 and through which opening the lower portion of the vent pipe 26 extends to the bottom wall 45 of the box 44. Also, descending fresh air enters through the opening 58 from the annular passages 30 and 34 and passes around the vent pipe 26 to the rectangular port 48 in the bottom 45 of the box 44 by which port 48 the air chamber 39 in the rearward element 38 is supplied. Thus, the approximately square plate 54 affords within the collar 56 a narrow forward shelf portion 54a immediately forward of the vent pipe 26 and desirably tangentially contacted thereby, and also lateral shelf portions. The inward edges of these shelf portions are welded to the top edges of the vertical walls of the box 44.

In order to centralize the lower end of the radiation pipe 32, a set of spring spacing clips 60 is provided, either on the inner wall of the collar 56, or mounted on the lower end of the radiation pipe 32 as shown.

For mounting the upper end of the outer air pipe 28 in the roof 14, a collar 62 having an attached flange 62a, as seen in FIGS. l and 4, is mounted and calked at 61 on top of the roof 14, and an upper end portion of the outer air pipe 28 extending above the roof is within the collar. This collar 62 which thus also surrounds the upper ends of the vent pipe 26 and the radiation pipe 32, acts to center the pipe 28 in the corresponding roof opening 63. The vent cap 25 is shown as including a short cylinder or ring 64 which acts as a wind-guard and is carried around an upwardly tapered rain-shedding cap 65 in suitably spaced relation by clips 66 or the like. This tapered disc or conical cap 65 acts to distribute the spent gases rising through the vent pipe 26, and also to exclude rain from the pipe 26 as well as from the pipes 28 and 32. For these purposes a sleeve member 68 depends in suitable relationship below the tapered cap 65, as by depending directly from a spaced large flange or annular plate 70 connected to the under side of the tapered cap 65 by spacing clips 72 or the like. The sleeve 68 fits over the upper end of the vent pipe 26, any appropriate spacing means, such as spring clips 73, being employed to retain concentric relationships between the sleeve 68, the pipe 26 and the pipe 32. The upper end of the collar 62 is secured by clips 74 to the plate 70 which thus imparts concentricity of the pipes 26 and 32 with the outer pipe 28. Of these pipes, the vent pipe 26 is the longest and reaches the plate 70. The outer pipe 28 may be the shortest and supplies cold combustion air. The pipe 32 may be intermediate in length as shown.

By such means, spent combustion gases rising through the concentric central vent pipe 26 are discharged above the plate 70 and below the tapered cap 65, and cool air is received under the plate 70 and through the annular channels 30 and 34, which air descends through the openings or ports 48 and 58 to feed the fresh air to the chamber 39 in the rearward element 38 and supply the burner 42 by way of the duct 40 leading to the lower end of the combustion chamber 36, as previously indicated.

Such a vent cap 25 as above described is shown on a much larger scale in FIG. 4 wherein the disc cap 65 is indicated as approximating a segment of a large sphere, as is the paralleling underlying annular plate 70. In this larger scale figure, the ring 64 is seen as having downturned and upturned reinforcing upper and lower inner flanges 64a to stiifen the structure materially. The assembly of FIG. 4 indicates the omission of the intermediate or radiation pipe 32 of FIG. 2, thus providing a single annular downdraft channel 30a. However, where desired, as when maximum heat is to be generated by an appropriate burner, the intermediate pipe 32 may be retained as indicated in FIG. 5. Thus, these parts are concentric and have a common vertical axis. In these structures it is desirable to provide means for limiting relative upward movement of the exhaust pipe 26 in the sleeve member 68, and of the outer air pipe 28 in the collar 62. For these purposes, the top of the collar 62 is provided with at least one overhanging tongue or finger 67 welded to the outer wall of the collar 62, against the under side of which tongue 67 the top of the outer pipe 28 may engage. Similarly, at least one overhanging tongue 67a is welded at the top of the sleeve member 68 against the under side of which the top of the exhaust pipe 26 may bear. These tongues 67 and 67a assure against relative movement of the pipes 28 and 26 above the tops of the collar 62 and the sleeve member 68 respectively, so as to avoid reduction of the air intake space under the plate 70 and of the exhaust discharge space under the disc cap 65. In order to insure a similar elevational relationship when the intermediate radiation pipe 32 is used, the lower ends of the spring clips 73 may be provided with offset fingers 73a to catch under the lower edge of the sleeve member 68.

In the particular form of heater illustrated in FIG. 2, the combustion element 35 includes a perpendicular rear wall 75 (approximately aligned with the forward wall of the box 44) anda forward wall 76 which desirably includes a downwardly and outwardly sloping portion 77 so that the lower portion of the combustion chamber 36 is somewhat enlarged. Near the upper end of the charnber 36 a bafl'le 78 is disposed in transverse relationship whereby to deflect the spent combustion gases laterally around its ends (which, as seen in FIG. 3, are spaced from the side walls 79 of the element 35) and facilitate heat absorption by the walls of the heater element 35, aswell as control draft. At the middle upper portion of the back wall 75, an outlet 80 is provided above the baffle 78. This outlet 80 communicates with a correspondly narrow partially cylindrical venting channel member 82 (FIG. 2) which is welded at its upper end around the circular port opening 46 to the bottom wall 45 of the box 44.

In this manner spent combusion gases pass from the chamber 36 by way of the outlet or discharge passage 80 into the venting channel member 82 and thence to the vent pipe 26.

As has previously been indicated, the forward heating element 35, which is in the nature of a combustion chamber, and the rearward element 38, which is in the nature of a cool air supplier, are rigidly connected together through the welded tubular duct 40 at their lower ends and through the sides of the overlying rectangular box 44, and also through the medium of its bottom wall 45, at their upper ends.

For the purpose of mounting the elements 35 and 38 in the housing or liner 22, the side walls of the latter are provided with vertical channel members 85 (FIG. 3). These channel'members provide vertical channels 86 for the passage of a portion of the air to be heated and taken from the living area of the trailer or other quarters in which the structure is installed. This air enters through the bottom of a grill 90 (FIGS. l and 2) secured at the front of the housing 22 and rises up around the heater unit 20. That air which rises through the channels 86 serves as an insulating medium to cool the side walls of the housing 22. The channel members 85, which also act as supporting members for the heater unit, carry brackets 92. To these brackets there is secured as by means of screws 93 a transverse intermediate supporting and positioning radiation plate 94, this plate being cut away to accommodate the tubular cool air duct 40 at the bottom of the structure and to accommodate the lower end of the rectangular box 44 and the spent-combustiongases discharge member 82.

For the purpose of mounting the heating unit 20, including the forward combustion chamber member 35 and the rearward cool air supplying member 38, upper and lower brackets 95 are welded at their opposite ends to the positioning plate 94 and the back wall 75 of the combustion chamber element 35. Similarly, upper and lower brackets 96 are Welded to the back of the transverse supporting wall or plate 94 and to the front wall 51 of the air supplying element 38. When the edges of the transverse plate 94 are secured to the 4brackets 92 by the screws 93, the entire heating unit is rigidly secured within the housing 22, and in spaced relation to all of the walls of the housing 22. Thus, air entering the lower portion of the housing 22, from the living space within the trailer being heated, rises partly through the lateral air channels 86, and partly up around the forward com- Y bustion chamber element 35 both forward and rearward of the latter. Some of the air also passes in behind the supporting and radiation wall 94 and rises up around the air supplying element 38 which gathers considerable heat through the supporting and radiation wall 94. Air which is heated convectionally by the combustion chamber element 35 passes outward through the upper portion of the combustion gases.

6 grill 90. Radiation heat also passes outward through the grill 90.

For the purpose of better controlling the discharge of the heated air from the upper portion of the housing 22, a pair of sloping baffles 98 and 99 are disposed above the heater unit 20. The lower baffle 98 deflects the heated air rising aronud the combustion chamber element 35 outward through the grill 90. This bale 98 is disposed between the two channel members 85. The upper baflle 99, which also is disposed between the two vertical channel members 85, cooperates with the underlying bae 98 to provide in air discharge through an upper portion of the grill for that portion of the air which rises around the air chamber member 38. The upper baille 99 extends to the back wall of the housing 22 and thus serves to deflect forward above it only that warmed air rising through the air channels 86 at the sides of the heating installation. Both these baffles are notched to accommodate the rectangular box 44.

The construction of the burner 42 is not a part of this invention, and any eicient approved gas burner is usable. It includes a control knob 100 and, if desired, a pilot light and thermostat control. A swinging door or cap 102 (FIG. 3) for controlling access to a lighting hole may also be provided as indicated. l

In the operation of the present structure, when the burner 42 is in operation, spent combustion gases rise to the top of the combustion chamber 36 and around the baffle 78, whence they pass out through the vent opening 80 and the channel member 82 and thence up through the vent pipe 26 to be discharged through the vent cap 25 above the roof. At the same time cold air enters from above the roof through the lower part of the vent cap 25 below the annular plate 70 into the outer air pipe 28 and downward by way of the annular air passages 30 and 34. Thence the cold air passes down into the rectangular box 44 around the lower end of the vent pipe 26 and enters the rectangular port 48 at the top of the air chamber 38, whence it travels to the bottom of such chamber and from that point through the duct 40 into the bottom of the combustion chamber 36 to supply the burner 42. By these means, only external air is used to support combustion, and air within the trailer is only recirculated over the heating elements for warming the living area of the trailer or other structure involved.

The functioning and arrangement of the parts of the vent cap 25 eliminate possible mixing of exhaust gases with the incoming cold air and are such as to exclude rain and spray. This is true because the disc cap 65 is annularly spaced from the ring 64 suiciently to accommodate all combustion gases which thus rise up along the inner wall of the ring 64 and because the annular plate 70 is annularly spaced from the ring 64 suliciently to insure air draft up through the annular space around the plate 70 and through the annular space 165 around the cap 65vunder draft influence of the rising hot Thus, only rising cold air can enter the space 168 around the sleeve 68 and beneath the plate. 70. Such rise of cold air to the space 168 may even be facilitated by the draft. For these purposes, the diameters of the cap 65 and the plate 70 are substantially equal.

At the same time, the ring 64 completely encloses the cap 65 and the plate 70, its upper edge extending above the disc cap 65 and its lower edge extending below the plate 70 and being substantially even horizontally with the upper end of the outer sleeve or collar 62. This arrangement effectually excludes all rain or spray from the vent pipe 26 and the collar 62. This is true even with winds.

Thus, these arrangements make it possible to place a gas heater of the indicated type in an interior wall rather than only in an outside wall. In either instance, the heater is installed between studs 15 which are adequately heat-insulated by the various described rising-air passages between the walls ofthe housing 22 and the heater elements 35 and 38. In such a heater, the height of the combustion chamber 35 and the air chamber 38, whose individual heights are about equal, is about twice their width; and the height of the box 44 extends such overall height about 20% or 25%. For example, in a typical common size, the height of the elements 35 and 38 is about eighteen inches and their width about eight t nine inches, while the box 44 adds approximately another four inches, Here, the thickness of each element 35 and 38 at their tops is about one inch, and they are spaced about two inches apart, with the radiation wall 94 disposed about equidistantly between them. This leaves adequate spacing, with a minimum of about one inch between the heater 20 as a whole and the walls of the housing 22, which housing may have a width of about eleven or twelve inches and a depth of about six and onehalf to seven inches. The vent pipe 26 typically is two inches in diameter, the outer air pipe 28 is four inches in diameter, and the intervening radiation pipe 32 is three inches in diameter. The ring 64 has a diameter of about eight and one-half inches and a width of about two inches, while the diameter of the disc 65 and the plate 70 is about seven inches. Spacings between the cap 65 and plate 70 of around three-fourths to one inch, and between the plate 70 and collar 62 of around one-half to threefourths inch, insure good draft and cold air entry. These parts extend upward from the top of the heater to a position above the roof, and commonly add another five to six feet in overall height.

It is thus seen that I have provided an improved sealedcombustion-chamber gas heater and vent cap for boats, mobile homes, larger homes, and the like, which make it possible and desirable to vent gaS-red heaters up through the roof and to locate them in interior walls as well as outer walls.

The invention claimed is:

1. In a heater vent cap to be disposed horizontally above a roof:

a rain and wind excluding ring in horizontal disposition and arranged about a vertical axis;

an upwardly tapering disc cap secured within said ring in spaced relation from said ring radially to provide a substantially annular venting space, the top of said ring lying above said disc cap;

an annular plate disposed in spaced relation below said cap to provide between the plate and cap a horizontal venting space for combustion gases leading to said annular venting space, said plate also being spaced radially from said ring to yield a substantially annular draft space therearound;

a positioning sleeve secured about a central Opening in said plate and extending downward to receive a vent pipe;

a mounting collar attached to said plate in spaced relation around said sleeve to provide a down-draft cold air passage between said sleeve and said collar; and

means mounting said plate in spaced relation above the top of said collar for admission of cold air to said passage.

2. A structure as in claim 1 including means on said collar and said sleeve to limit upward movement of pipes therein.

3. A structure as in claim 1 wherein the top of said collar is substantially horizontally even with the bottom of said ring to exclude rain.

References Cited by the Examiner UNITED STATES PATENTS 2,764,972 10/56 Ryder 126-307 2,856,837 10/58 Thulman 98-46 2,909,113 10/59 Hatcher 98-46 JAMES W. WESTHAVER, Primary Examiner. 

1. IN A HEATER VENT CAP TO BE DISPOSED HORIZONTALLY ABOVE A ROOF: A RAIN AND WIND EXCLUDING RING IN HORIZONTAL DISPOSITION AND ARRANGED ABOUT A VERTICAL AXIS; AN UPWARDLY TAPERING DISC CAP SECURED WITHIN SAID RING IN SPACED RELATKON FROM SAID RING RADIALLY TO PROVIDE A SUBSTANTIALLY ANNULAR VENTING SPACE, THE TOP OF SAID RING LYING ABOVE SAID DISC CAP; AN ANNULAR PLATE ABOVE IN SPACED RELATION BELOW SAID CAP TO PROVIDE BETWEEN THE PLATE AND CAP A HORIZONTAL VENTING SPACE FOR COMBUSTION GASES LEADING TO SAID ANNULAR VENTING SPACE, SAID PLATE ALSO BEING SPACED RADIALLY FROM SAID RING TO YIELD A SUBSTANTIALLY ANNULAR DRAFT SPACE THEREAROUND; A POSITIONING SLEEVE SECURED ABOUTA CENTRAL OPENING IN SAID PLATE AND EXTENIDNG DOWNWARD TO RECEIVE A VENT PIPE; A MOUNTING COLLAR ATTACHED TO AID PLATE IN SPACED RELATION AROUND SAID SLEEVE TO PROVIDE A DOWN-DRAFT COLD AIR PASSAGE BETWEEN SAID SLEEVE AND SAID COLLAR; AND MEANS MOUNTING SAID PLATE IN SPACED RELATION ABOVE THE TOP OF SAID COLLAR OF ADMISSION OF COLD AIR TO SAID PASSAGE. 